Injection system



July 30, 1946. D. E. MEITZLER 2,405,043

INJECTION SYSTEM Filed May 11, 1943 FIG! FIG. 2 INVENTOR Mama 6% C24 ATTORNEY Patented July 30, 1946 INJECTION SYSTEM Donald E. Meitzler, Manchester, Conn., assignor to United Aircraft Corporation, East Hartford, Conn a corporation of Delaware Application May 11, 1943, Serial No. 486,623

- 1 Claim. 1

This invention relates to injection systems of the type in which fuel i accumulated under pressure in a chamber, the outlet of which is con trolled by a spring-pressed valve which is opened by a drop in the fuel supply pressure.

In prior devices of this character, the accumulator valve is held closed by the fuel pressure, an the pressure drop, which has caused the valve to open, has been obtained by opening a relief valve in the fuel supply connection. A check valve generally incorporated in the inlet to the accumulator chamber to maintain pressure in this chamber when the supply pressure drops. An object of this invention is to avoid the necessity for the relief valve by controlling the accumulator valve for the chamber by a pump plunger which. during its stroke, relieves the pressure in the pump and causes the discharge of fuel from the chamber.

Another feature of this invention i the control of the quantity of fuel discharged from the chamber on each injection, by an adjustment of the pump plunger. This adjustment does not change the position of the plunger stroke at which the pump pressure is relieved.

Other objects and advantages will be apparent from the specification and claim, and from the accompanying drawing which illustrates what is now considered to be a preferred embodiment of the invention.

Fig. 1 is a sectional view through the pump and the injection nozzle.

Fig. 2 i a fragmentary sectional view of the check valve in the nozzle.

Fig. 3 is a perspective view of the end of the injection plunger.

The injection system is adapted for use With an engine having a cylinder in which air is compressed by a piston, With fuel injected into the cylinder at or near the end of the compression stroke of the piston.

The pump 4 is actuated by a cam 6, the movements of which may be synchronized with the piston stroke of the engine. The pumping stroke normally occur during the compression stroke of the engine. During this period, the pump delivers fuel under pressure to an accumulator nozzle 8, and at a predetermined point, a sudden drop in pump pressure causes injection of fuel from noz zle 8 into the engine cylinder 9.

The injection nozzle 8 includes a housing I!) threaded at l2 to engage a threaded bore in the wall of the engine cylinder. A sleeve l4 fits within the hollow housing and at the end adjacent to the threads I2 is reduced in diameter at l6 to discharged into the engine cylinder. A cap 28 engages the opposite end of sleeve i4 and is clamped within housing ii! by a threaded ring 22. Sleeve l4 forms an accumulator chamber 2-3 in which fuel is accumulated under pressure in readiness for injection.

Within chamber 24 is an accumulator valve including a plunger 26 having a valve element 28 at one end engaging a valve seat 29 in sleeve M for closing delivery port l8. This plunger is normally held against seat 29 by a coil spring 39 surrounding the plunger and extending between flange 32 on the plunger and cap 20. Plunger 28 is a sliding fit Within sleeve l4 between flange 32 and valve element 28 and has a longitudinal groove 34 to permit a flow of fuel from chamber 24 to discharge port IB.

An inlet passage 36 in cap 26 has a concentric valve seat 38 engaged by a valve element 45 on the end of plunger 26 remote from valve element 28. Between seat 38 and the accumulator chamber, cap 20 has a bore 42 forming a continuation of passage 36 and in which the end of plunger 25 is guided. A bypass channel 44, Fig. 2, in cap 213 permits the flow of fuel from passage 33 into the accumulator chamber. Channel 44 has a check valve 45 which prevents reverse flow from chamber 24 into passage 36.

During delivery of fuel under pressure to the accumulator chamber, the pressure acting on valve element 49 assists spring in holding the plunger against seat 29 for closing port 18. Upon a sudden drop in pressure in passage 36, the greater pressure within the accumulator chamber causes the plunger to move endwise until valve element engages seat 38. This endwise movement of the plunger opens port l8 for injection of fuel from the accumulator chamber into the engine cylinder. Injection continues until the plunger is moved by spring 30 to close port IS.

The operation of the injection nozzle is controlled by the pump 4. This pump has a housing 46 in which a sleeve 48 is clamped by a threaded holder 55. A nipple 52 is clamped between the end of the holder and the sleeve.

The pump plunger 54 is reciprocated in sleeve 48 by the cam 6. Thi plunger ha a head 56 engaging a cup 58 reciprocating in a bore 68 in the housing. Cup 58 has a pin 6| supporting a roller 62 which engages cam 6. A coil spring 64 engaging a washer carried by the plunger head 56 holds this head against the cup and keeps the cam roller in engagement with the cam.

In addition to its reciprocation, plunger 54 may be turned within the sleeve for adjusting the quantity of fuel injected on each stroke. For this purpose a ring 66 surrounds the lower end of sleeve 48 and is notched to engage with projections 68 on the plunger. Ring 66 ha teeth engageable with a rack 61 slideable in housing 46. The position of this rack determines the angular position of the pump plunger.

Sleeve 48 has a filling port and a spill or discharge port 12 both communicating with a fuel supply port 74 in the housing. Plunger 54 has a longitudinal groove 16 extending from the upper end of the plunger to an annular groove 18 in the plunger. Between groove 18 and the end of the plunger. one side wall of groove 76 forms an obliquely extending shoulder 86'by which to control the quantity of injected fuel by adjusting the position of the stroke at which the filling port is covered by the plunger.

The end of the pump bore above plunger 54 is connected to passage 36in the injection nozzle by a passage 82 in cap 50 and a pipe 84.

A the plunger begins its pumping stroke, filling port 16 is first covered by plunger 54. As the plunger movement continues, shoulder 80 covers the spill port 52 and prevents further escape of fuel from the sleeve 48 at the end of the plunger. Continued plunger movement forces fuel under pressure into the accumulator chamber until ports 16 and 12 are uncovered by groove 18. When this occurs, pressure at the end of the pump plunger drop suddenly by reason of the discharge of fuel through grooves 16 and 18 and through ports H1 and 12. Port 12 is larger than filling port H! and the greater part of the fuel spill through this port. A corresponding drop in pressure on the end of valve plunger 26 causes this plunger to move against valve seat 38. Check valve 45 is closed at this time and prevents escape of fluid from chamber 24 through channel 44. Movement of valve plunger 26 opens port 18, and fuel accumulated in chamber 24 discharges through the port until spring 30 returns the plunger 26 into the position shown, in which port I8 is again closed.

By this arrangement, injection results from a drop in pressure at the end of the pump plunger, although this drop in pressure does not materially affect the fuel pressure in the accumulator chamber. Injection continues until spring 30 overcomes the pressure in the chamber and closes port I8. Angular adjustment of the pump plunger, which changes the effective pumping stroke of the plunger, thereby controls the quantity of fuel forced into the accumulator chamber and accordingly controls the quantity of fuel discharged from the chamber on each injection.

Spill port 12. as shown, i an elongated slot in sleeve 48 to provide a, large flow area when this port is uncovered. The large port area makes possible a rapid drop in the pressure in passage 82 to provide the desired movement of the valve plunger 26.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit a defined by the following claim.

I claim:

Injection apparatus including a housing, a sleeve within said housing having a valve seat at one end, a cap within said housing closing the opposite end of the sleeve and defining therein a chamber, said cap having a passage therethrough and a valve seat in said passage in alignment with the valve seat at the opposite end of the sleeve, 2. plunger Within the sleeve having one end fitting within and guided by the passage in the cap and engageable with the valve seat therein, the other end of the plunger engaging the seat at the end of the sleeve, and a spring surrounding said plunger and urging said plunger against the seat in the sleeve.

DONALD E. MEITZLER. 

